Abrasive grinding apparatus



July 18, 1967 l. G. WINER ABRASIVE GRINDING APPARATUS 2 Sheets-Sheet lFiled NOV. 19, 1965 July 18, 1967 l. G. wlNER 3,331,164 ABRASIVEGRINDING APPARATUS Filed Nov. 19, 9 5

1 6 2 Sheets-Sheet 2 F/q. 3 Z9 ATTORNEYS United States Patent C)3,331,164 ABRASIVE GRINDING APPARATUS Irving G. Winer, 3241 KentuckyAve. S., St. Louis Park, Minn. 55426 Filed Nov. 19, 1965, Ser. No.508,728 6 Claims. (Cl. 51-144) This application is acontinuation-in-part of my copending application Ser. No. 325,284 filedNov. 21, 1963,

for Cam Finishing Apparatus, now Patent No. 3,222,- 822 issued Dec. 14,1965.

This invention relates to abrasive grinding apparatus, one example ofwhich is apparatus for finishing cams and similar parts requiringsmoothly finished edge surfaces. The invention is described withparticular reference to apparatus for providing edge cams with a highlypolished precision finish on their Working edge faces, but it will beunderstood that the principles of the invention as claimed are adaptableto other grinding applications.

The invention is illustrated in the accompanying drawings in which thesame numerals are used to identify corresponding parts and in which:

FIGURE 1 is a perspective view of a cam finishing apparatusincorporating the present invention;

FIGURE 2 is a top plan view of the apparatus;

FIGURE 3 is a fragmentary front elevation, partly in section taken onthe line 3-3 of FIGURE 2 and in the direction of the arrows, of thefinishing portion of the apparatus; and

FIGURE 4 is a fragmentary and enlarged transverse section, on the line4-4 of FIGURE 2 and in the direction of the arrows.

Referring now to the drawings, the apparatus as illustrated comprisesgenerally a base supporting a frame or standard 11 which in turnsupports a fiat horizontal top working platform 12. On one side of theapparatus there is mounted a motor 14 supported by a bracket 15 andhaving a driven shaft 16, to which is attached a drum 17. An endlessbelt 18 carrying a coating of fine abrasive material on its outersurface is driven by the motor through the shaft 16 and drum 17.

On the top platform 12 of the apparatus, spaced back from the sidemounting the motor 14 there is a bracket 19 which supports a rocker arm21 for pivotal movement on a shaft 20 carried in the bracket. At theopposite end of the rocker arm 21 from its axis of rotation about thepivot 20 there is journalled a spindle 22 for rotation relative to therocker arm, and preferably for simultaneous reciprocating motion. Shaft20 and spindle 22 are both preferably journalled in hardened steelbushings for minimum wear and maximum life.

Spindle 22 is rotated by virtue of attachment to the drive shaft of asecond motor 23 mounted on a plate 27. The plate is provided with a slot28 at one end which engages the shaft 20 so as to hold the motor againstrotation relative to the rocker arm, so as to impart rotary motion tothe spindle.

As described hereinafter, it is desirablev that the spindle 22reciprocate relative to the rocker arm 21 so as to distribute wearuniformly across the abrasive belt 18. One means of accomplishing suchreciprocation is provided by a face cam 24 fixed to the spindle 22 forrotation therewith. A rotary cam follower 25 mounted on a shaftsupported by a post or bracket 26 mounted on the top of the rocker arm21 bears against the working face of the cam 24. Aplurality of coilsprings 30 extending between the plate 27 mounting the motor 23 andposts 29 extending on opposite sides of the rocker arm resiliently anduniformly urge the cam follower 25 against the face of the cam 24 at alltimes. As the spindle 22 rotates the cam 24 causes the motor 23 and theplate 27 supporting 3,331,164 Patented July 18, 1967 the motor to beurged closer to and farther away from the rocker arm causing reciprocalmovement of the spindle relative to the rocker arm.

The cam 32 to be finished is supported at the free end of the spindle 22on the opposite side of the rocker arm 21 from the motor 23 andreciprocating cam 24. The cam 32 to be finished is secured to thespindle for rotation therewith along with a master cam 31 whose contoursare desired to be exactly duplicated in the cam to be finished.

One means by which the master cam and cam to be finished may be mountedfor rotation together is shown in FIGURES 3 and 4. A sleeve 33 of brassor other nonmagnetic material is fitted with a plurality oflongitudinally extending magnets 34 whose ends are co-planar with theends of the sleeve 33. The cam 32 to be finished and the master cam 31are butted up against the opposite ends of the sleeve 33 and held thereby the attractive force of the magnets. The cams are located andpositioned relative to one another by means of a timing pin 35 extendingthrough the sleeve and projecting from the end faces of the sleeve tofit into a locating hole provided in each of the cams for purposes ofalignment. The sleeve 33 is secured to the spindle by means of a setscrew 36. It will be readily seen that both cams will rotate andreciprocate with the spindle and with each other simultaneously.

A pair of solid stable blocks extend upwardly from the top of theplatform. The first of these blocks 38 underlies the spindle and firmlyand solidly supports a small diameter pin 37, preferably formed fromwear resistant tool steel, spaced below and in approximate verticalalignment with the spindle. This pin 37 functions as a cam follower forthe master cam 31. The sleeve 33 and master cam 31 are so positioned onthe spindle 22 that as the spindle rotates and reciprocates the edges ofthe master cam will at all times be in position to be in contact withthe pin 37. The effect of this is that the master cam causes the rockerarm, along with the spindle and motor 23 and associated mechanism, tomove on the rocker arm pivot up or down depending upon the particularcontour of the master cam in contact with the follower pin at anyinstant.

The other projecting block 40 is spaced from the first and firmly andsolidly supports a second static pin 39, desirably formed from hard Wearresistant and heat resistant ceramic material, such as alumina or thelike. The endless abrasive belt passes over this pin and the edges ofthe cam 32 to be finished move in contact with the abrasive belt as itpasses around the pin and as the cam 32 rotates with the spindle. Thepin 39 is in alignment with the master cam follower pin 37 but is oflesser radius by an amount equal to the thickness of the abrasive belt,in order to insure that the cam to be finished will have the exactdimensions as the master cam. Typically, pin 39 may be of the order ofM1 inch diameter and may range from about G to 1 inch in diameter. Asmay be seen from the drawings, drive drum 17 is of substantially greaterdiameter than pin 39, so that the peripheral speed of belt 18 around pin39 is many times the peripheral speed around the drum. As seen in FIGURE1, but best seen in FIGURE 4, the path of travel of belt 18 from drum 17to pin 39 is at a small acute angle relative to the path of travel ofthe belt from the pin to the' drum, and the belt is in contact with thepin surface over more than about 1/3 of its periphery.

By means of the apparatus of the present invention cam edges haveconsistently been provided with finishes in the range from 2.1 to 2micro-inch finish. The apparatus, according to the present invention, isnot limited to the finishing of convex contours but has successfully andconsistently finished cams whose surfaces have concave as well as convexcontours.

It is apparent that many modifications and variations of this inventionas hereinbefore set forth may be made without departing from the spiritand scope thereof. The speciic embodiments described are given by way ofexample only and the invention is limited only by the terms of theappended claims.

I claim:

1. A precision, .abrasive ygrinding apparatus comprising:

(A) a stationary supporting frame,

(B) a static abrasive web supporting pin mounted at one end on saidframe,

(C) a drive means mounted on said frame,

(D) said drive means being spaced from said static pin and including acylindrical driven drum, and

(E) an endless abrasive web extending tautly in a continuous loop aroundsaid static pin to said drive means and around said drum, the path oftravel of said web from said drive means to said static pin dening asmall acute angle with the path of travel of said web from said staticpin to said drive means, and said web being in contact with the surfaceof said pin over more than about 1/3 of its periphery.

2. An apparatus according to claim 1 further characterized in that saidstatic pin is of substantially smaller diameter relative to the diameterof said drive drum, whereby rotation of said drum causes rapid movementof said abrasive web over said pin.

3. An apparatus according to claim 2 further characterized in that saidpin is from about 3716 to l inch diameter.

4. An apparatus according to claim 1 further characterized in that saidstatic pin is composed of hard wear resistant and heat resistant ceramicmaterial.

5. An apparatus according to claim 1 further characterized in that saiddrive means comprises an electric motor having said drum secured to itsdriven shaft, the axis of said driven shaft being parallel to the axisof said static pin. v

6. An apparatus according to claim 1 further characterized by thepresence of a cam follower pin supported from said frame and in axialalignment with said abrasive web supporting pin, said cam follower pinhaving a radius greater than the radius of said web supporting pin bythe thickness of said web, means for holding a cam to be finished and amaster cam resiliently against said web and cam follower pin,respectively, and means for moving said holding means and cams relativeto said pins.

References Cited UNITED STATES PATENTS 880,663 3/1908 Hermann 51-1411,150,155 8/1915 Sumner 51-135 3,222,822 12/1965 Winer 51-101 X ROBERTC. RIORDON, Primary Examiner.

D. G. KELLY, L. S. SELMAN, Assistant Examiners.

1. A PRECISION, ABRASIVE GRINDING APPARATUS COMPRISING: (A) A STATIONARYSUPPORTING FRAME, (B) A STATIC ABRASIVE WEB SUPPORTING PIN MOUNTED ATONE END ON SAID FRAME, (C) A DRIVE MEANS MOUNTED ON SAID FRAME, (D) SAIDDRIVE MEANS BEING SPACED FROM SAID STATIC PIN AND INCLUDING ACYLINDRICAL DRIVEN DRUM, AND (E) AN ENDLESS ABRASIVE WEB EXTENDINGTAUTLY IN A CONTINUOUS LOOP AROUND SAID STATIC PIN TO SAID DRIVE MEANSAND AROUND SAID DRUM, THE PATH OF TRAVEL OF SAID WEB FROM SAID DRIVEMEANS TO SAID STATIC PIN DEFINING A SMALL ACUTE ANGLE WITH THE PATH OFTRAVEL OF SAID WEB FROM SAID STATIC PIN TO SAID DRIVE MEANS, AND SAIDWEB BEING IN CONTACT WITH THE SURFACE OF SAID PIN OVER MORE THAN ABOUT1/3 OF ITS PERIPHERY.